Printing arrangement for high-speed teleprinters



Jan. 26, 1965 w. SCHIEBELER 3,167,166

PRINTING ARRANGEMENT FOR HIGH-SPEED TELEPRINTERS Filed April 4, 1961 3 Sheets-Sheet 1 Fly] INVENTOR F! .Sch iebe ler BY W ATTORNEY Jan. 26, 1965 w. SCHIEBELER 3,167,166

PRINTING ARRANGEMENT FOR HIGH-SPEED TELEPRINTERS 3 SheetsSheet 2 Filed April 4, 1961 Fig. 2

Fig.3

Velocity Path Length of Line b 1 ATTORNEY Jan. 26, 1965 w, scm EL 3,167,166

PRINTING ARRANGEMENT FOR HIGH-SPEED TELEPRINTERS Filed April 4, 1961 3 Sheets-Sheet 3 Fig. 4

POI/7 5 w 5 .E 2 B 2 S 0, c :1 I l I Time 1'- v v t INVENTOR mschiebeler ATTORNEY United States Patent 3,167,166 PRINTING ARRANGEMENT FOR HIGH-SPEED TELEPRINTERS Werner Schiebeler, Eutingen, Baden, Germany, assignor to International Standard Electric Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 4, 1961, Ser. No. 100,680 Claims priority, application Germany, Apr. 7, 1960, St 16,328 6 Claims. (Cl. 1971) The present invention relates to a printing arrangement for output devices and, more particularly, to highspeed teleprinters in which the printing element slides in a line-wise manner on the paper fixed in the horizontal direction.

As is well-known, teleprinters or printing output devices for data-processing systems, which are not intended to print a complete line at a time, usually comprise a carriage which is advanced in a step-by-step manner in the printing direction, and carries the printing elements (type bars, type wheels, or the like).

This carriage, when arriving at the end of the line, is returned as quickly as possible to the beginning of the line. This process is known as the carriage return.

In the case of printers with a printing speed exceeding that of about 10 letters per second, attempts have already been made, especially in view of reducing the mass of the printing elements, to produce the printed character not by striking the type bar, but by composing the character of raster points (picture points or elements). In this case the carriage would only have to carry a small number of needle elements which, quite depending on the kind of apparatus, would be between 5 and 35.

However, despite the reduction of the mass of the printing carriage achieved by this arrangement, the time required for the necessary carriage return cannot be reduced below 100 microseconds. When printing speeds of characters per second are reached, this carriagereturn time involves a loss of two character lengths. In the case of still higher printing speeds the relative loss of time is also correspondingly higher.

In this connection the difiiculty still exists of always having to interrupt the operation of the transmitter during the time of the carriage return, in order that no text of the message is lost. The transmitter, when controlled e.g. by perforated tapes, is supposed to operate as continuously as possible. If a stoppage of the transmitter is impossible, then a number of blank signals (letters or space) have to be punched into the perforated tape containing the message, which number of blank signals corresponds to the time required by the carriage return. In producing the tape, however, this causes some difficulties or at least inconveniences. In any case the transmission path is not fully utilized on account of the non-operative times caused by the carriage return.

FIG. 1 shows an arrangement designed in accordance with the state of prior art. This arrangement which operates on the screen-print principle permits the achievement of high printing speeds in the case of a continuous or step-by-step carriage movement.

The paper tape on a paper reel P is led round a platen W. In back of the paper, a printing head SK is mounted on a movable carriage. This head is capable of sliding from the left to the right over the paper in the printing direction, and from the end of the line back to the initial position.

The printing head SK contains the printing elements which, in the described arrangement, consist of five needles. These needles are electromagnetically operated Bdfiifllhh Patented Jan. 26, 1965 and are selectively pressed against the paper, or it is possible to produce a spark discharge through the paper between the needles and the platen W; and it is also possible to change the color of the paper electrolytically by means of a passage of current. The shown arrangement also permits the carrying out of a xerographic or electrographiic operation.

The details of the possible printing method are of no particular importance in this connection. It is merely essential that a readable point or spot is produced on the paper upon applying an electric voltage to an inscribing needle.

In the arrangement shown in FIG. 1 the five inscribing needles are controlled by the transistors T1 to T5. If, during the continuous forward movement of the printing head SK, a negative pulse is applied to a transistor via one of the terminals K1 to KS, then the associated needle will produce a pointer spot on the paper. By a column-wise setup of the characters an intelligible or readable print will appear in the conventional manner on the paper. In this connection it is necessary that coded pulses are applied in a suitable way to the transistors.

In such a printing arrangement, to avoid a nonoperative time caused by the necessary carriage return at the end of the line, a printing device is proposed in accordance with the invention, in which two printing heads move slidingly back and forth over the paper in a reciprocal movement in the same rhythm and within two adjoining partial sections which, together, form one length of a line. In this arrangement the two printing heads are controlled in such a way that they only print when being moved in the printing direction.

In the following, the invention is described with reference to FIGS. 2-4 of the accompanying drawings.

FIG. 2 is a schematic of one embodiment of the invention.

FIG. 3 is a diagram of the course of the speed as a function of the path of the writing head.

FIG. 4 is the path-time diagram of the writing heads.

All nonessential parts of the drive have been left out in FIG. 2. For the sake of clarity, even the record paper that normally lies against the platen W, has not been drawn in.

The arrangement of FIG. 2 contains the two writing heads SKI and 8K2, both of which are rigidly connected to carriages S1 and S2. The carriages are moved back and forth, each over a halfwidth of the paper, by means of a spindle drive. The spindle drive consists of spindle shaft AW, which has two endless superimposed worm gears running to the left and to the right. Carriages S1 and S2 travel over the worm gears and are controlled in their direction of motion by shuttles Sfl and S72. These shuttles also reverse both carriages at the end of the worm gears.

The movement of the two carriages and of the two writing heads is explained as follows:

When S1 is at the left-hand end of the spindle shaft AW, S2 is at the right-hand end of the spindle. When shaft AW turns, S1 moves to the right and S2 to the left. In the center of the spindle, and thus also in the middle of the paper, both carriages and writing heads come together. The ground covered by the two writing heads is so arranged that when the two rows of writing needles come together in the center of the paper, they are a very short distance apart and the writing areas add up to a total of one line. The shuttles then reverse the carriage, with Sfl slipping into that portion of the worm gear running to the left and Sf2 into that portion running to the right. S1 now moves to the left and S2 to the right.

FIGS. 3 and 4 show the exact movements. The speedpath curve is shown in FIG. 3. On the forward run along the path s=0 to s=b/ 2, writing head 8K1 has the constant speed v From s=b/2 on, SEQ is slowed down to speed 0 and then accelerated in the opposite direction. This corresponds to the return of the writing head. From s=b/ 2 to s=b (a complete line), writing head 8K2 moves at speed v over the right-hand half of the paper. When it arrives at the rig t-hand end of the line, at s=b, SKT has also again reached the point 5:0 and has already reached the forward speed v From now on, 8K2 is slowed down and then accelerated in the opposite direction. This interplay repeats itself periodically for each new line. The path/time diagram shown in FIG. 4 results from what has just been set forth above.

As may be seen from FlGS. 3 and 4, higher speeds are required to return the writing heads than to advance the. because the time lost at the points of reversal must be made up.

The writing-head drive arrangement shown in H6. 2 is only one of the possible embodiments. Drive mechanisms are conceivable that do not work with endless right and left worm gears but have only a simple worm gear on the drive shaft and by reversing the drive shaft move the writing heads alternately to the left and to the right. Drives operating over pull cords and the like are also conceivable. The only essential thing is that the movement of two writing heads in opposite directions is achieved. The writing heads need not necessarily move continuously, as in the example of FIG. 2. They may also be driven step-by-step for each letter.

FIG. 2 also shows the electric drive of the writing needles. In order to simplify the drawing, only the control of the two uppermost needles of writing heads SK]. and S112 is shown. These two needles are connected to the collectors of transistors T2 and T3. Both transistors are controlled simultaneously by transistor T1 over resistances R3 and R5. Over terminal K1 and resistance R1, transistor T1 receives control pulses that represent the coding of the symbol about to be written.

To prevent both writing needles from printing the same letters at the same time, a bistable flip-flop is provided, consisting of trans stors T4 and T5. The collectors of transistors T4- and T 5 are connected across diodes DE and D2 to resistances Rd and R2. The circuit operates as follows:

When transistor T4 is open, all control currents are shunted over resistance R5 to tl e general reference point and as a result transistor T3 is constantly blocked. During this time, however, transistor T5 is blocked and switched out of the base circuit of transistor T2 by diode D2. The transistor is thus free to conduct current in cadence with the control signals provided by transistor T1 and produces raster points on the paper through the uppermost writing needle of writing head 5K2.

The situation changes when the flip-lop flips, opening transistor T5 and blocking transistor T4. In that case, the uppermost writing needle of writing head 5K1 is ready to operate, while that of writing head SE2 is switched out by blocked transistor T2. There are as many diodes D1 and D2 and transistors T2 and T3 as there are writing needles on the writing heads.

The electrical condition of the flip-flop indicates which of the two Writing heads is being controlled at the moment and which one is inoperative.

' In developing the invention still further, a reversing arrangement is provided that allows the writing head that is advancing at the moment and has reached the constant speed v to print. The reversal operation must take place, first when the writing heads are at the points s=0 and 5:1) and again when they are at the points s=b/ 2.

in accordance with the embodiment shown in MG. 2, a disk Ls is provided, driven by drive shaft AW over a notched belt Z. The reducing gear ratio between drive shaft and disk is so chosen that disk Ls makes one revolution while the writing heads complete one forward and return movement.

Disk Ls has two holes that in passing electric bulb L let a light beam St through so that it can fall on photoelectric transistor PT and open it. The moment the light hits the photoelectric transistor and opens it, a positive pulse is sent across condenser C to the input of the flipilop consisting of transistors T4- and T5 and the flip-flop flips, causing a reversal in the action of the writing heads.

Since there are two holes L01 and L02 set 180 apart in disk Ls, such reversal occurs twice during one complete forward and backward movement. The position of holes L01 and L02 must be so adjusted that they let the light beam through just at the moment when the writing heads are at the points s=0 and s=b or at s=b/2.

Further measures not shown in FIG. 2 must be taken to bring the flip-flop into the proper output position so that the writing heads print when they are advancing and not during their return. To this end, for example, another hole in the disk and another photoelectric transistor could be provided, in which case the photoelectric transistor, should the flip-flop be in the wrong flip position, would flip it into the proper position. In order to make it easier to understand how the reversal arrangement operates, the setting of holes L01 and L02 in the arrangement shown in FIG. 2 is not represented correctly. It is not in line with the above requirements. The holes would have to be shifted by about 90.

Reversing the writing heads, which in accordance with FTG. 2 is done photoelectrically, can also be done differently. For example, it can be done by attaching two cams to disk Ls that actuate a contact mechanically in place of the photoelectric transistor.

An electrostatic or magnetic scanning of markings on disk Ls is also possible.

Furthermore, the position of writing heads SKI and 8K2 can be directly scanned, mechanically, photoelectrically, electrostatically or electrcmagnetically.

In place of the writing heads with raster needles described in the embodiment, writing heads with other printing means, type wheels for example, can also be used.

The arrangement heretofore described and shown in FIG. 2 was based on the premise that drive shaft AW and thus the direction of movement of writing heads SKT and 3K2 were made to run parallel to the axis of platen W. With constant printing such an arrangement produces a somewhat slanted line on paper P, due to the fact that during printing the paper is constantly being advanced beneath the writing heads. In order to obtain a line at right angles to the edge of the paper with no slant, it is necessary to tilt drive shaft AW with respect to platen W so that the slant due to the paper advance is in this way straightened out.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. A printing arrangement for high-speed teleprinters comprising means for holding a record blank against linewise movement, two printing heads mounted for reciprocal linewise movement with respect to said record blank and respectively within two adjoining sections which together form one line length, means for simultaneously and reciprocally moving said heads within said sections in opposite directions, and control means for causing said heads to print on said record blank only when said heads are moving in the printing direction.

2. A printing arrangement, as defined in claim 1, in which the means for moving the printing heads comprises means for moving them at constant speed in the printing direction and for decelerating the speed at the point of reversal, accelerating the speed in the counter-printing direction to a speed greater than said constant speed, decelerating the speed again at the second point of reversal, and accelerating the speed again to said constant spee in the printing direction.

3. A printing arrangement, as defined in claim 1, in which the control means comprises a flipdiop circuit, and means for causing said circuit to shift from one stable condition to the other depending on the positions of the printing 1 eads.

4. A printing arrangement, as defined in claim 3, in Which the means for moving the printing heads comprises a rotatable shaft and the means for causing the flip-flop circuit to SLlft comprises a disk, means for rotating said disk at a predetermined speed with respect to said shaft, and means on said disk for causing said flip-flop circuit to shift at predetermined positions of said disk, the speeds of said shaft and disk being such that one rotation of the disk corresponds With one complete backward and ior- Ward movement of the printing heads.

5. A printing arrangement, as defined in claim 4, in which the means on the disk for causing the flip-flop circuit to shaft comprises a pair of diametrically spaced holes on said disk, a light source mounted in a fixed position on one side of said disk, light sensitive means mount- 6 ed in fixed position on the other side of said disk so as to receive li -ht from said source as said holes pass between said source and said light sensitive means, and means for connecting the output of said light sensitive means to said flip-flop circuit.

6. A printing arrangement for high-speed teleprinters comprising means for holding a record blank against linewise movement, two printing means mounted for reciprocal linewise movement with respect to said record blank respectively Within two adjoining sections which together from one line length, means for simultaneously and reciprocally moving said printing means Within said sections in opposite directions, and control means for causing said printing means to print on said record blank only when said printing means are moving in the printing direction.

Cited in the file of this patent UNITED STATES PATENTS 

1. A PRINTING ARRANGEMENT FOR HIGH-SPEED TELEPRINTERS COMPRISING MEANS FOR HOLDING A RECORD BLANK AGAINST LINEWISE MOVEMENT, TWO PRINTING HEADS MOUNTED FOR RECIPROCAL LINEWISE MOVEMENT WITH RESPECT TO SAID RECORD BLANK AND RESPECTIVELY WITHIN TWO ADJOINING SECTIONS WHICH TOGETHER FORM ONE LINE LENGTH, MEANS FOR SIMULTANEOUSLY AND RECIPROCALLY MOVING SAID HEADS WITHIN SAID SECTIONS IN OPPOSITE DIRECTIONS, A CONTROL MEANS FOR CAUSING SAID HEADS TO PRINT ON SAID RECORD BLANK ONLY WHEN SAID HEADS ARE MOVING IN THE PRINTING DIRECTION. 